She isn't sure why she does it. She sees Sarah lift her cross of a blade over Mugen and starts to feel her legs move. She doesn't remember when she landed on top of him until she feels the blood from his wound starting to seep in to her kimono. "Stop." She thinks she says. "Please no more." But later on she'll know that those aren't the exact words.
Mugen will ask her why. They'll have stopped in a small town on the way, and Jin will have left for a few minutes to meditate, and he'll ask. "Why'd you do it Fuu?" Fuu will look at him like he's cross eyed, but he's looking out the open screen door. "You said 'If I lost you I don't know what I'd do' but you could just get someone else."
Fuu will stop giving him that look and won't answer for a while, but will finally sense his annoyance and let out a huge sigh. "I don't know."
"You don't love me do ya'? Cause I don't need no fuckin' dame gettin' all clingy or nothing." He will say, turning back to her, pointing a finger accusingly at her. "Fall in love with Jin all you want, but if fuckin' fall in love with me I'll kill ya'.
She'll roll her eyes at his machismo; look him straight in the eyes and say: "I'm not in love with you."
"Good. Don't answer why you did what you did."
She'll remember what she had figured out later, before he had woken up and she had told him that. "I did it because I figured if I had to get a new body guard with as much baggage as you or Jin I would end up traveling until I died." She would pause, not for dramatic effect, but because the words tasted so sour on her mouth. "I would never reach Nagasaki."
Mugen would stand, and he would give her that look. That trademark Mugen look that makes the hairs on the back of her neck stand up, and makes her start wringing her hands nervously. "So you're basically sayin' if me or Jin ain't here you're worth shit."
Fuu would frown, "Well when you put it like that," she would continue to wring her hands under his gaze. "I guess it is like that." She would stand, and stretch a little bit. "So if you go out tonight don't get yourself killed. G'night."
Mugen would stand there for a few minutes after she had closed the divider, staring at that divider like it would suddenly turn into a large amount of cash. Any second now. "Fuck it." He would finally say, before venturing out into the night.
I was kind of bored. I had just watched the episode. I don't think this is any good, but decided what ever.